spring boot 学习2 application

太过爱你忘了你带给我的痛 2022-02-09 14:19 190阅读 0赞

### 定义：Spring应用引导类，提供便利的自定义行为方法。 ###

# #

## **SpringApplication 运行3种** ##

@SpringBootApplication
    public class ApplicationNewDemo {
    
        public static void main(String[] args) {
            SpringApplication.run(ApplicationNewDemo .class, args);
        }

public static void main(String[] args) {
            Set<String> sources = new HashSet<>();
            sources.add(MyApplication.class.getName());
    
            SpringApplication application = new SpringApplication();
            application.setSources(sources);//添加bean
            //REACTIVE和SERVLET都有时会使用SERVLET
            application.setWebApplicationType(WebApplicationType.SERVLET);
            application.setAdditionalProfiles("Cat","Dog");//添加profile
            ConfigurableApplicationContext context = application.run(args);
            System.out.println("bean: " + context.getBean(MyApplication.class));
        }
    
        @SpringBootApplication
        public static class MyApplication{ }

@SpringBootApplication
    public class ApplicationBuilderDemo {
    
        public static void main(String[] args) {
            new SpringApplicationBuilder(ApplicationBuilderDemo.class)
                    .bannerMode(Banner.Mode.CONSOLE)
                    .web(WebApplicationType.NONE)
                    .profiles("Cat","Dog")
                    .headless(true)
                    .run(args);
        }
    }

## **推断** ##

web模式推断：Servlet、Reactive同时存在使用Servlet，只存在一个使用存在的（通过实现类是否存在判断：Reactive -》DispatcherHandler，Reactive -》DispatcherServlet）

推断引导类：通过堆栈classpath查找使用main作为方法名的方法。

## **配置上下文初始化器** ##

**这个时候是bean加载之前，只能做一些初始化操作**

**通过order实现加载顺序（值是int类型，越大优先级越小），2种方法（@order/实现order接口）效果一样**

@Order(Ordered.HIGHEST_PRECEDENCE)
    public class OneApplicationContextInitializer<C extends ConfigurableApplicationContext>
            implements ApplicationContextInitializer<C> {
        @Override
        public void initialize(C applicationContext) {
            System.out.println("One ApplicationContext.id = "+ applicationContext.getId());
        }
    }

public class TwoApplicationContextInitializer implements ApplicationContextInitializer, Ordered {
    
        @Override
        public void initialize(ConfigurableApplicationContext applicationContext) {
            System.out.println("Two application.id = " + applicationContext.getId());
        }
    
        @Override
        public int getOrder() {
            return Ordered.LOWEST_PRECEDENCE;
        }
    }

META-INF.spring.factories

# ApplicationContextInitializer 实现配置
    org.springframework.context.ApplicationContextInitializer=\
    com.stude.gray.spring_boot.application.context.TwoApplicationContextInitializer,\
    com.stude.gray.spring_boot.application.context.OneApplicationContextInitializer

## **添加事件监听 ApplicationListener ** ##

**模拟监听上下文完成事件**

public class HelloWorldApplicationListener implements ApplicationListener<ContextRefreshedEvent> {
        @Override
        public void onApplicationEvent(ContextRefreshedEvent event) {
            System.out.println("HelloWorld : " + event.getApplicationContext().getId()
                    + " , timestamp : " + event.getTimestamp());
        }
    }

META-INF.spring.factories

# ApplicationListener 实现配置
    org.springframework.context.ApplicationListener=\
    com.stude.gray.spring_boot.application.listener.HelloWorldApplicationListener

**在上下文中注册监听器，并发布监听事件**

public static void main(String[] args) {
            // 创建上下文（none）
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
            //创建上下文（Servlet）
    //AnnotationConfigServletWebServerApplicationContext context = new AnnotationConfigServletWebServerApplicationContext();
            //创建上下文（Reactive）
    // AnnotationConfigReactiveWebServerApplicationContext context = new AnnotationConfigReactiveWebServerApplicationContext();
    
            // 注册应用事件监听器
            context.addApplicationListener(event -> {
                System.out.println("监听到事件: " + event);
            });
    
            // 启动上下文
            context.refresh();
            // 发送事件
            context.publishEvent("HelloWorld");
            context.publishEvent("2018");
            context.publishEvent(new ApplicationEvent("小马哥") {
    
            });
    
            // 关闭上下文
            context.close();
        }

**添加运行时监听器**SpringApplicationRunListener

public class HelloWorldRunListener implements SpringApplicationRunListener {
        
        //必须要有这个构造器
        public HelloWorldRunListener(SpringApplication application, String[] args) {
    
        }
    
        @Override
        public void starting() {
            System.out.println("HelloWorldRunListener.starting()...");
        }
    
        @Override
        public void environmentPrepared(ConfigurableEnvironment environment) {
    
        }
    
        @Override
        public void contextPrepared(ConfigurableApplicationContext context) {
    
        }
    
        @Override
        public void contextLoaded(ConfigurableApplicationContext context) {
    
        }
    
        @Override
        public void started(ConfigurableApplicationContext context) {
    
        }
    
        @Override
        public void running(ConfigurableApplicationContext context) {
    
        }
    
        @Override
        public void failed(ConfigurableApplicationContext context, Throwable exception) {
    
        }
    }

META-INF.spring.factories

org.springframework.boot.SpringApplicationRunListener=\
    com.stude.gray.spring_boot.application.listener.HelloWorldRunListener

**各监听阶段说明**

<table> 
 <thead> 
  <tr> 
   <th>监听方法</th> 
   <th style="width:504px;">执行位置</th> 
   <th style="width:313px;">监听事件</th> 
  </tr> 
  <tr> 
   <th>starting()</th> 
   <th style="width:504px;">Spring 应用刚启动</th> 
   <th style="width:313px;">&nbsp;ApplicationStartingEvent&nbsp;</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>environmentPrepared(ConfigurableEnvironment)</td> 
   <td style="width:504px;">ConfigurableEnvironment 准备妥当，允许将其调整&nbsp;</td> 
   <td style="width:313px;">&nbsp;ApplicationEnvironmentPreparedEvent&nbsp;</td> 
  </tr> 
  <tr> 
   <td>contextPrepared(ConfigurableApplicationContext)&nbsp;</td> 
   <td style="width:504px;">ConfigurableApplicationContext 准备妥当，允许将其调整</td> 
   <td style="width:313px;">&nbsp;</td> 
  </tr> 
  <tr> 
   <td>contextLoaded(ConfigurableApplicationContext)</td> 
   <td style="width:504px;">ConfigurableApplicationContext 已装载，但仍未启动&nbsp;</td> 
   <td style="width:313px;">&nbsp;ApplicationPreparedEvent&nbsp;</td> 
  </tr> 
  <tr> 
   <td>started(ConfigurableApplicationContext)</td> 
   <td style="width:504px;">ConfigurableApplicationContext 已启动，此时 Spring Bean 已初始化完成</td> 
   <td style="width:313px;">&nbsp;ApplicationStartedEvent&nbsp;</td> 
  </tr> 
  <tr> 
   <td>running(ConfigurableApplicationContext)&nbsp;</td> 
   <td style="width:504px;">Spring 应用正在运行</td> 
   <td style="width:313px;">&nbsp;ApplicationReadyEvent&nbsp;</td> 
  </tr> 
  <tr> 
   <td>failed(ConfigurableApplicationContext,Throwable)</td> 
   <td style="width:504px;"> <p>Spring 应用运行失败&nbsp;</p> </td> 
   <td style="width:313px;">&nbsp;ApplicationFailedEvent&nbsp;</td> 
  </tr> 
 </tbody> 
</table>

### 启动完成回调接口 ###

二者基本一样，区别在于接收的参数不一样。CommandLineRunner的参数是最原始的参数，没有做任何处理，而ApplicationRunner的参数是ApplicationArguments，对原始参数做了进一步的封装。

@Component
    public class ServerStartedReport implements CommandLineRunner {
        @Override
        public void run(String... args) throws Exception {
            for(String ars : args){
                System.out.println(ars);
            }
            System.out.println("===========CommandLineRunner启动====="+ LocalDateTime.now());
        }
    }

@Component
    public class MyApplicationRunner implements ApplicationRunner{
    
        @Override
        public void run(ApplicationArguments args) throws Exception {
            System.out.println("ApplicationRunner："+ Arrays.asList(args.getSourceArgs()));
            System.out.println("getOptionNames："+args.getOptionNames());
            System.out.println("getOptionValues："+args.getOptionValues("foo"));
            System.out.println("getOptionValues："+args.getOptionValues("log"));
        }
    }

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关闭上下文

@RestController
    public class Hello {
    
        @Autowired
        ConfigurableApplicationContext context;
    
        @RequestMapping("/hello")
        public String getHello(){
    
            context.close();
            return "ok~~";
        }
    }

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